Why is upgrading a lengthy procedure?

My question is: Why is upgrading from one version of Oracle to another such a difficult and lengthy procedure?

Background to the question:

I=B4m have a long experience in Oracle Rdb (former DEC Rdb) but I have=  limited
experience in Oracle7 or other versions of Oracle.

I have never performed the upgrade of an Oracle system but from discussions between people who have, I have understood that this is not something you do in an hour or two.

If I compare to something I have done many times, upgrade of Oracle Rdb, it IS something you CAN do in an hour or two. The upgrade of Oracle Rdb will take much less then two hours on most systems. The only thing that could take a lot more time is to test all application programs and databases under the new version before upgrading to avoid surprises after upgrading... This is normally done on a separate test system OR on the production system using the multiversion capability of Oracle Rdb. (Multiversion means that you can run several versions of the DBMS at the same time while you can let every user use the version of his choice.)
Name: Magnus Weiman
Company: Datalogikonsult AB
mailto:WEIMANM_at_DECUS.SE
S-mail: Box 52, S-590 61 VRETA KLOSTER, SWEDEN Phone: +46 13 131330
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minicall text: 393662 Received on Tue Mar 14 1995 - 03:39:24 CST